There is often a need for relocating a functional unit of one particular size and type in a different location on the deck which has a rectangular opening that is perhaps larger and is intended for some other type of unit. An example of such need is one wherein the functions fulfilled by the units in various locations on a ship-deck have to be changed because of a change in strategy or a different approach or even simply to improve the efficiency of the layout of the several units on the ship-deck, depending on particular circumstances. There may also be need for installing a smaller readily available unit in a larger opening on a ship-deck, pending arrival of the proper unit. Yet another situation is encountered wherein units may have to be relocated from a smaller ship to a larger ship where the mounting facilities for the functional units may be different.
Invariably, the functional units have an integral base in the form of a platform structure, and the openings on the ship-decks have reinforcing substructures around the perimeter of the openings for stiffening purposes.